Ringworm, a common infection of the skin, hair and nails, is caused by a:

Despite its name, ringworm is not caused by a worm at all. It is a common skin infection caused by a group of fungi called dermatophytes, belonging mainly to the genera Trichophyton, Microsporum and Epidermophyton. These fungi feed on keratin, the protein found in the outer layer of the skin, hair and nails. The medical name for ringworm is tinea.

The name "ringworm" comes from the typical appearance of the infection: a red, itchy, scaly, circular or ring-shaped patch on the skin, often clearer in the middle with a raised edge, which looks a little like a worm curled into a ring.

Ringworm is named according to the part of the body affected:

• Tinea corporis: on the body.
• Tinea capitis: on the scalp, common in children, sometimes causing patches of hair loss.
• Tinea pedis: on the feet, commonly called athlete's foot.
• Tinea cruris: in the groin area, called jock itch.
• Tinea unguium (onychomycosis): in the nails.

The fungi grow best in warm, moist conditions. Ringworm spreads by direct contact with an infected person or animal (such as cats and dogs), or by sharing items such as towels, combs, clothes and bedding. It is common in hot and humid climates and in crowded living conditions.

Treatment usually involves antifungal creams or ointments, such as clotrimazole, miconazole and terbinafine, and, for severe or scalp infections, antifungal tablets. Prevention includes keeping the skin clean and dry, not sharing personal items, and wearing loose cotton clothes. In recent years, India has seen a rise in difficult-to-treat dermatophyte infections, partly due to the misuse of steroid creams.

Other common fungal diseases in humans include candidiasis (thrush) and the dangerous mucormycosis ("black fungus"), which affected many COVID-19 patients in India in 2021.

Why not the other options?

• ✗Worms (helminths) cause diseases such as ascariasis and filariasis, not ringworm.
• ✗Viruses cause diseases such as measles, chickenpox and influenza.
• ✗Good to know
• ✗Bacteria cause diseases such as tuberculosis, cholera and typhoid.